Catalyst comprising a hydrogenation metal and a delaminated layered silicate

ABSTRACT

There is provided a catalyst comprising at least one hydrogenation metal, such as Ni and Mo, supported on a delaminated layered silicate, such as kenyaite, which has been swollen and calcined. There is also provided a method for making this catalyst. There is further provided a process for using this catalyst to demetalize a petroleum feedstock, such as a gas oil.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of copending U.S. applicationSer. No. 07/644,149, filed Jan. 22, 1991 now U.S. Pat. No. 5,137,861,the entire disclosure of which is expressly incorporated herein byreference.

BACKGROUND

There is provided a catalyst comprising at least one hydrogenationmetal, such as Ni and Mo, supported on a delaminated layered silicate,such as kenyaite, which has been swollen and calcined. There is alsoprovided a method for making this catalyst. There is further provided aprocess for using this catalyst to demetalize a petroleum feedstock,such as a resid.

In general, calcined layered materials, i.e. clays, silicates, and metaloxides, exhibit low surface areas (<50 m² /g) and are not attractive ascatalysts supports. The activity and surface areas of these materialscan be enhanced by swelling and pillaring. In the case of the silicates,i.e. kenyaite and magadiite, the activity enhancement would be afunction of the pillaring material used. The improvement in the surfacearea and porosity would be a function of the extent of swelling and/orpillaring. However, the pore openings (or layered spacings) are limitedby the stability of the pillaring agents. In addition, the pillars couldcause additional diffusion resistance, depending on the homogeneity ofthe pillaring process. Some reactions, such as demetallation of heavyhydrocarbons, require very large pore openings (>50 Angstroms) to reducediffusion resistance of the bulky metal-containing molecules. Evenlarger cylindrical type pores (50-200 Angstroms) can be rapidlydeactivated by the building up of deposited metals from the heavyhydrocarbons. Catalysts supports with unique pore shapes (i.e.cone-shaped morphology) that can reduce the pore-mouth plugging arehighly desirable. Alumina supports with such desirable pore morphologyhave been discussed by H. Toulboat et al. in U.S. Pat. Nos. 4,498,972;4,499,203; 4,501,042; and 4,511,458, as well as "New HDM Catalysts:Design and Performance for Demetallation and Conversion", ACS Div.Petroleum Chemistry, Vol. 30, No. 1, pp. 85-95 (1985). These aluminamaterials are formed by a rapid calcination of an organic treatedamorphous alumina.

SUMMARY

There is provided a catalyst comprising at least one hydrogenation metalsupported on a non-pillared, delaminated layered silicate lackingoctahedrally coordinated sheets of clays.

There is also provided a method for making a catalyst, said catalystcomprising at least one hydrogenation metal supported on a delaminatedlayered silicate lacking octahedrally coordinated sheets of clays, saidmethod comprising the steps of:

(i) contacting said layered silicate with a swelling agent underconditions sufficient to incorporate said swelling agent into theinterspathic region of said layered silicate and to separate the layersof said layered silicate;

(ii) calcining the swollen layered silicate of step (i) under conditionssufficient to delaminate the layers of said layered silicate; and

(iii) combining the layered silicate of step (ii) with at least onehydrogenation metal.

There is further provided a process for demetalizing a petroleumfeedstock, said process comprising contacting said petroleum feedstockwith a catalyst under sufficient demetallation conditions, said catalystcomprising at least one hydrogenation metal supported on a delaminatedlayered silicate lacking octahedrally coordinated sheets of clays.

EMBODIMENTS

Low surface area layered silicates (e.g.; unswollen, calcined kenyaite;<50 m² /g surface area) can be converted to high surface area supports(150-200 m² /g) by thermally treating the preswollen form. Evaluation ofa NiMo impregnated kenyaite after this type of treatment showed goodactivity for the demetallation of Arabian Light atmospheric resid.

Layered silicates are composed of tetrahedral sheets condensed on eachother and lack the octahedral sheets found in clays. Layered silicatesare "non-water-swellable" which is intended to distinguish fromconventional clays which contain octahedrally coordinated metal oxidesheets bonded to tetrahedrally coordinated silica sheets and whichundergo substantial swelling sometimes by an essentially unboundedamount, when contacted with water. As used herein in relation to alayered silica material, the term "non-water-swellable" is defined asmeaning a layered silicate material, which, when contacted with at least10 grams of water per gram of the layered silicate at 23° C. for 24hours, exhibits an increase in d-spacing no greater than 5 Angstroms ascompared with the material before treatment. Included among thesematerials are the metasilicates. Layered silicates, e.g., high silicaalkali silicates such as magadiite, natrosilite, kenyaite, makatite,nekoite, kanemite, okenite, dehayelite, macdonaldite and rhodesite,unlike swellable clays, lack octahedral sheets, i.e., sheets composed ofatoms which are octahedrally coordinated with oxygen atoms.

The layered silicates known as high silica alkali silicates whose layerslack octahedral sheets can be prepared hydrothermally from an aqueousreaction mixture containing silica and caustic at relatively moderatetemperatures and pressures. These layered silicates may containtetracoordinate framework atoms other than Si. Such layered silicatescan be prepared by co-crystallizing in the presence of non-silicontetravalent elements, e.g., those selected from the group consisting ofAl, B, Cr, Fe, Ga, In, Ni, Zr as well as any other such elements whichare catalytically useful when incorporated in the silicate structure.Alternatively, non-silicon framework elements already in a layeredsilicate may be substituted by a tetracoordinate element. For example,kenyaite containing boron in its framework when treated with aluminumnitrate results in a kenyaite which contains aluminum in its framework.Both co-crystallized and substituted layered high silica alkalisilicates may be methods described herein.

Synthetic magadiite is readily synthesized hydrothermally from areaction mixture containing inexpensive sources of silica and caustic.Tetracoordinate elements other than silicon, e.g., those selected fromthe group consisting of Al, B, Cr, Fe, Ga, In, Ni, Zr and othercatalytically useful metals, may be added to the reaction mixture toproduce synthetic magadiite layered silicates. Preferably, such elementsare selected from the group consisting of Al and Fe. An organicdirecting agent may also be added to the reaction mixture. The reactionmixture for synthetic magadiite materials can be described in molarratios as follows:

    ______________________________________                                        SiO.sub.2 X.sub.2 O.sub.3 =                                                                  10 to infinity where X can be Al,                                             B, Cr, Fe, Ga, and/or Ni or other                                             catalytically useful metal                                     M.sup.+ OH.sup.- /SiO.sub.2 =                                                                0 to 0.6 (preferably 0.1-0.6)                                                 M = any alkali metal                                           H.sub.2 O/SiO.sub.2 =                                                                        8-500                                                          R/SiO.sub.2 =  0-0.4                                                          ______________________________________                                    

where R can be an organic such as benzyltriethylammonium chloride,benzyltrimethylammonium chloride, dibenzylmethylammonium chloride,N,N'-dimethylpiperazine, triethylamine, or other quaternary compounds orheterocyclic amines.

The reaction mixture can be maintained at a temperature of about 100°to200° C. for anywhere from about 1 to 150 days in order to form a producthaving the following composition:

% N=0-3, e.g., 0 to 0.3

SiO₂ /X₂ O₃ =10 to infinity where X may be in the tetrahedral oroctahedral position

M₂ O/SiO₂ =0 to 5.0, e.g., 0.05-0.1

Kenyaite, a layered silicic acid which is known to exist in nature as asodium salt Na₂ Si₂₂ O₄₅ H₂ O can be prepared in the potassium form K₂Si₂₂ O₄₅ 10H₂ O in the laboratory. Synthetic kenyaite is readilysynthesized hydrothermally from a reaction mixture containinginexpensive sources of silica and caustic, preferably KOH.Tetracoordinate elements other than silicon, e.g., those selected fromthe group consisting of Al, B, Cr, Fe, Ga, In, Ni, Zr and othercatalytically useful metals, may be added to the reaction mixture toproduce synthetic kenyaite. Al(NO₃)₃.9H₂ O and aluminum-tri-sec-butoxideare suitable reagents for the introduction of non-silicontetracoordinate elements in the kenyaite framework. Co-crystallizingwith B, Al, and/or Zr is particularly preferred. The reaction mixturemay also be seeded with kenyaite.

It will be understood that the terms, magadiite and kenyaite, as usedherein, connote synthetic forms of the naturally occurring substances ofthe same structure. For example, naturally occurring magadiite has beenfound in Lake Magadi, Kenya.

The layered silicate may be swollen by methods discussed in U.S. Pat.No. 4,859,648, the entire disclosure of which is expressly incorporatedherein be reference.

These layered silicates may be swollen by treatment with a swellingagent. Such swelling agents are materials which cause the layers toseparate by becoming incorporated into the interspathic region of theselayers. The swelling agents are removable by calcination, preferably inan oxidizing atmosphere, whereby the swelling agent becomes decomposedand/or oxidized.

Suitable swelling agents may comprise a source of organic cation, suchas organoammonium cation, in order to effect an exchange of theinterspathic cations. Suitable organoammonium cations includecetyltrimethylammonium cations. A pH range of 7-10 may be employedduring treatment with the swelling agent.

The foregoing treatment results in the formation of a layered silicateof enhanced interlayer separation depending upon the size of the organiccation introduced. In one embodiment, a series of organic cationexchanges can be carried out. For example, an organic cation may beexchanged with an organic cation of greater size, thus increasing theinterlayer separation in a step-wise fashion. Contact of the layeredsilicate with the swelling agent is conducted in aqueous medium so thatwater is trapped between the layers of the swollen species.

Insertion of the organic cation between the adjoining layers serves tophysically separate the layers. In particular, alkylammonium cationshave been found useful. Thus C₃ and larger alkylammonium, e.g.,cetyltrimethylammonium, cations are readily incorporated with theinterlayer spaces of the layered silicate serving to prop open thelayers. The extent of the interlayer spacing can be controlled by thesize of the organoammonium ion employed.

After calcination to remove the organic propping agent, the delaminatedproduct may contain residual exchangeable cations. Such residual cationsin the layered silicate can be ion exchanged by known methods with othercationic species to provide or alter the catalytic activity of thedelaminated product. Suitable replacement cations include cesium,cerium, cobalt, nickel, copper, zinc, manganese, platinum, lanthanum,aluminum, ammonium, hydronium and mixtures thereof.

The layered silicates described herein are used in intimate combinationwith a hydrogenating component such as tungsten, vanadium, molybdenum,rhenium, nickel, cobalt, chromium, manganese, or a noble metal such asplatinum or palladium. Particular Groups of the Periodic Table fromwhich the hydrogenation metal may be selected include Group VI (Cr, Mo,W) and Group VIII (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt). Suchcomponent can be exchanged into the composition, impregnated therein orintimately physically admixed therewith. Contacting of the layeredsilicate with the hydrogenating component preferably takes place aftercalcination of the layered silicate. Such component can be impregnatedin, or on, the layered silicate such as, for example, by, in the case ofplatinum, treating the layered silicate with a solution containing aplatinum metal-containing ion. Thus, suitable platinum compounds forthis purpose include chloroplatinic acid, platinous chloride and variouscompounds containing the platinum amine complex.

The layered silicate is subjected to thermal treatment, e.g., todecompose organoammonium ions. This thermal treatment is generallyperformed by heating one of these forms at a temperature of at leastabout 370° C. for at least 1 minute and generally not longer than 20hours. While subatmospheric pressure can be employed for the thermaltreatment, atmospheric pressure is preferred simply for reasons ofconvenience. A rapid calcination of the swollen silicate is preferred toaccomplish the delamination of the layered silicate.

Prior to its use in demetallation processes described herein, thelayered silicate catalyst is preferably dehydrated, at least partially.This dehydration can be done by heating the crystals to a temperature inthe range of from about 200° C. to about 595° C. in an atmosphere suchas air, nitrogen, etc., and at atmospheric, subatmospheric orsuperatmospheric pressures for between about 30 minutes to about 48hours. Dehydration can also be performed at room temperature merely byplacing the layered silicate in a vacuum, but a longer time is requiredto obtain a sufficient amount of dehydration.

The layered silicate catalyst can be shaped into a wide variety ofparticle sizes. Generally speaking, the particles can be in the form ofa powder, a granule, or a molded product such as an extrudate having aparticle size sufficient to pass through a 2 mesh (Tyler) screen and beretained on a 400 mesh (Tyler) screen. In cases where the catalyst ismolded, such as by extrusion, the layered silicate can be extrudedbefore drying or partially dried and then extruded.

It may be desired to incorporate the layered silicate with anothermaterial which is resistant to the temperatures and other conditionsemployed in the catalytic processes described herein. Such materialsinclude active and inactive materials and synthetic or naturallyoccurring zeolites as well as inorganic materials such as clays, silicaand/or metal oxides such as alumina. The latter may be either naturallyoccurring or in the form of gelatinous precipitates or gels includingmixtures of silica and metal oxides. Use of a material in conjunctionwith layered silicate, i.e., combined therewith or present during itssynthesis, which itself is catalytically active may change theconversion and/or selectivity of the catalyst. Inactive materialssuitably serve as diluents to control the amount of conversion so thatproducts can be obtained economically and orderly without employingother means for controlling the rate of reaction. These materials may beincorporated into naturally occurring clays, e.g., bentonite and kaolin,to improve the crush strength of the catalyst under commercial operatingconditions. Said materials, i.e., clays, oxides, etc., function asbinders for the catalyst. It is desirable to provide a catalyst havinggood crush strength because in commercial use, it is desirable toprevent the catalyst from breaking down into powder-like materials.These clay binders have been employed normally only for the purpose ofimproving the crush strength of the catalyst.

Naturally occurring clays which can be composited with layered silicatesinclude the montmorillonite and kaolin family, which families includethe subbentonites, and the kaolins commonly known as Dixie, McNamee,Georgia and Florida clays or others in which the main mineralconstituent is halloysite, kaloinite, dickite, nacrite, or anauxite.Such clays can be used in the raw state as originally mined or initiallysubjected to calcination, acid treatment or chemical modification.Binders useful for compositing with layered silicates also includeinorganic oxides, notably alumina.

In addition to the foregoing materials, the layered silicates can becomposited with a porous matrix material such as silica-alumina,silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia,silica-titania as well as ternary compositions such assilica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesiaand silica-magnesia-zirconia.

The relative proportions of finely divided layered silicates andinorganic oxide matrix vary widely, with the layered material contentranging from about 1 to about 90 percent by weight and more usually,particularly when the composite is prepared in the form of beads, in therange of about 2 to about 80 weight of the composite.

The demetallation conditions used for demetalizing the petroleumfeedstock may include a temperature of 400°-900° F. (204°-482° C.), apressure of 100-5000 psig, and a weight hourly space velocity of 0.1-10.

EXAMPLE 1

Air-dried as-synthesized kenyaite was combined with a 0.1Mcetyltrimethylammonium chloride solution (prepared by mixing 875milliliters of H₂ O with 125 milliliters of a 29% by weightcetyltrimethylammonium chloride solution) in a weight ratio of kenyaiteto solution of 1:2. This slurry was allowed to mix overnight. Theproduct was filtered and the procedure was repeated a second time. Theproduct from the second treatment was filtered and washed with water andair-dried. The chemical analyses were:

    ______________________________________                                        K                    930    ppm                                               SiO.sub.2            38.6   wt. %                                             Ash, 1000° C. 38.5   wt. %                                             ______________________________________                                    

The X-ray pattern of the swollen material showed a major peak atapproximately 36 Angstroms, consistent with a swollen layered materialwhose layers are separated by approximately 18 Angstroms (the layerthickness of kenyaite is approximately 18 Angstroms).

EXAMPLE 2

One hundred grams of the product of Example 1 was combined with 150grams of water and divided into four equal portions. The first portion(A) was dried in a hot pack (250° F.). The second portion (B) was driedin a conventional microwave oven (6 minutes at 95% power). A thirdportion (C) was dried using a laboratory scale spray drier at atemperature of 150° C. The fourth portion (D) was dried with the spraydrier at 200° C. Each sample was then calcined at 540° C. for ten hoursin air. The surface areas and average pore sizes of the four calcinedmaterials are shown in Table I. SEM photographs of Example 2C illustratethat the thermal treatment delaminated the layered material providingincreased surface area and porosity for catalytic processing. The X-raypattern of Example 2C showed major peaks at 17.5 and 3.4 Angstroms,which was consistent with the kenyaite structure.

EXAMPLE 3

One hundred grams of the product of Example 1 was combined with 150grams of ethanol and divided into four equal portions. The first portion(A) was dried in a hot pack (250° F.). The second portion (B) was driedin a conventional microwave oven (5 minutes at 95% power). A thirdportion (C) was dried using a laboratory scale spray drier at atemperature of 150° C. The fourth portion (D) was dried with the spraydrier at 200° C. Each sample was then calcined at 540° C. for ten hoursin air. The surface areas and average pore sizes of the four calcinedmaterials are shown in Table I.

EXAMPLE 4

One hundred grams of the product of Example 1 was combined with 150grams of ethylene glycol and divided into four equal portions. The firstportion (A) was dried in a hot pack (250° F.). The second portion (B)was dried in a conventional microwave oven (30 minutes at 90%). A thirdportion (C) was dried using a laboratory scale spray drier at atemperature of 150° C. The fourth portion (D) was dried with the spraydrier at 200° C. Each sample was then calcined at 540° C. for ten hoursin air. the surface areas and average pore sizes of the four calcinedmaterials are shown in Table I.

COMPARATIVE EXAMPLE

As-synthesized kenyaite was calcined at 540° C. The surface area was 6.8m² /g and the average pore size was 153 Angstroms.

                  TABLE I                                                         ______________________________________                                        Surface areas and Average Pore Size                                           Example   Surface area, m.sup.2 /g                                                                    Average Pore Size, A                                  ______________________________________                                        2A        224           81                                                    2B        195           93                                                    2C        169           75                                                    2D        173           97                                                    3A        222           87                                                    3B        234           89                                                    3C        171           77                                                    3D        180           85                                                    4A        213           91                                                    4B        177           97                                                    4C        --            --                                                    4D        199           89                                                    ______________________________________                                    

EXAMPLE 5

Thirty-eight grams of product from Example 1 was blended with 16.5 gramsof Ultrasil, a precipitated silica. This blend was impregnated (using aroto-vap) with a solution of 3.32 grams of (NH₄)₆ Mo₇ O₂₄ 4H₂ Odissolved in a 15% (by weight) cetyltrimethylammonium chloride/watersolution. The sample was dried at 110° C. overnight and then calcined inair at 540° C. for three hours. This material was then impregnated(using a roto-vap) with a solution of 2.47 grams of Ni(NO₃)₂.6H₂ Odissolved at 31.86 grams of water. The catalyst was again dried at 110°C. overnight and calcined at 540° C. in air for three hours. Thechemical analyses and physical properties were:

    ______________________________________                                        Ni, wt %          1.55                                                        Mo, wt %          4.7                                                         Ash, 1000° C.                                                                            98.1                                                        Surface area, m.sup.2 /g                                                                        143                                                         ______________________________________                                    

EXAMPLE 6

The product from Example 5 was pelleted, crushed, and sized to 14/24mesh for evaluation as a demetallation catalyst. After presulfiding, thematerial was tested in a fixed-bed pilot unit for demetallation ofArabian Light atmospheric resid (Table II) at 0.5 LHSV, 1900 psig H₂pressure, and at 650°, 700°, 725°, and 750° F. The results aresummarized in Table II.

                  TABLE II                                                        ______________________________________                                        Arabian Light Atmospheric Resid                                               ______________________________________                                               Gravity, °API                                                                     18.1                                                               Sulfur, wt %                                                                              3.0                                                               Nickel, ppmw                                                                              8.9                                                               Vanadium, ppmw                                                                           34.0                                                               Distillation, wt %                                                                       °C.                                                         10         320                                                                30         407                                                                50         476                                                                70         558                                                         ______________________________________                                    

                  TABLE III                                                       ______________________________________                                        Demetallation Performance                                                            Temperature, °F.                                                                  HDM, %                                                      ______________________________________                                               650        50.7                                                               700        65.6                                                               725        72.0                                                               750        81.9                                                        ______________________________________                                    

What is claimed is:
 1. A catalyst comprising at least one hydrogenationmetal supported on a non-pillared, delaminated layered silicate lackingoctahedrally coordinated sheets of clays.
 2. A catalyst according toclaim 1, wherein said layered silicate is magadiite or kenyaite.
 3. Acatalyst according to claim 1, wherein said layered silicate iskenyaite.
 4. A catalyst according to claim 1, wherein said catalystcontains a Group VI metal and a Group VIII metal.
 5. A catalystaccording to claim 3, wherein Ni and Mo are supported on saiddelaminated layered silicate.
 6. A catalyst according to claim 1,wherein said delaminated layered silicate has a surface area of at least150 m² /g.
 7. A catalyst according to claim 1, wherein said delaminatedlayered silicate has a surface area of 150-200 m² /g.